diff --git a/client.go b/client.go
index 227f43a4..07bb46b3 100644
--- a/client.go
+++ b/client.go
@@ -207,6 +207,33 @@ func (a *Agent) Set(k, v string) *Agent {
 	return a
 }
 
+// SetBytesK sets the given 'key: value' header.
+//
+// Use AddBytesK for setting multiple header values under the same key.
+func (a *Agent) SetBytesK(k []byte, v string) *Agent {
+	a.req.Header.SetBytesK(k, v)
+
+	return a
+}
+
+// SetBytesV sets the given 'key: value' header.
+//
+// Use AddBytesV for setting multiple header values under the same key.
+func (a *Agent) SetBytesV(k string, v []byte) *Agent {
+	a.req.Header.SetBytesV(k, v)
+
+	return a
+}
+
+// SetBytesKV sets the given 'key: value' header.
+//
+// Use AddBytesKV for setting multiple header values under the same key.
+func (a *Agent) SetBytesKV(k []byte, v []byte) *Agent {
+	a.req.Header.SetBytesKV(k, v)
+
+	return a
+}
+
 // Add adds the given 'key: value' header.
 //
 // Multiple headers with the same key may be added with this function.
@@ -217,6 +244,36 @@ func (a *Agent) Add(k, v string) *Agent {
 	return a
 }
 
+// AddBytesK adds the given 'key: value' header.
+//
+// Multiple headers with the same key may be added with this function.
+// Use SetBytesK for setting a single header for the given key.
+func (a *Agent) AddBytesK(k []byte, v string) *Agent {
+	a.req.Header.AddBytesK(k, v)
+
+	return a
+}
+
+// AddBytesV adds the given 'key: value' header.
+//
+// Multiple headers with the same key may be added with this function.
+// Use SetBytesV for setting a single header for the given key.
+func (a *Agent) AddBytesV(k string, v []byte) *Agent {
+	a.req.Header.AddBytesV(k, v)
+
+	return a
+}
+
+// AddBytesKV adds the given 'key: value' header.
+//
+// Multiple headers with the same key may be added with this function.
+// Use SetBytesKV for setting a single header for the given key.
+func (a *Agent) AddBytesKV(k []byte, v []byte) *Agent {
+	a.req.Header.AddBytesKV(k, v)
+
+	return a
+}
+
 // ConnectionClose sets 'Connection: close' header.
 func (a *Agent) ConnectionClose() *Agent {
 	a.req.Header.SetConnectionClose()
@@ -231,6 +288,13 @@ func (a *Agent) UserAgent(userAgent string) *Agent {
 	return a
 }
 
+// UserAgentBytes sets User-Agent header value.
+func (a *Agent) UserAgentBytes(userAgent []byte) *Agent {
+	a.req.Header.SetUserAgentBytes(userAgent)
+
+	return a
+}
+
 // Cookie sets one 'key: value' cookie.
 func (a *Agent) Cookie(key, value string) *Agent {
 	a.req.Header.SetCookie(key, value)
@@ -238,6 +302,20 @@ func (a *Agent) Cookie(key, value string) *Agent {
 	return a
 }
 
+// CookieBytesK sets one 'key: value' cookie.
+func (a *Agent) CookieBytesK(key []byte, value string) *Agent {
+	a.req.Header.SetCookieBytesK(key, value)
+
+	return a
+}
+
+// CookieBytesKV sets one 'key: value' cookie.
+func (a *Agent) CookieBytesKV(key, value []byte) *Agent {
+	a.req.Header.SetCookieBytesKV(key, value)
+
+	return a
+}
+
 // Cookies sets multiple 'key: value' cookies.
 func (a *Agent) Cookies(kv ...string) *Agent {
 	for i := 1; i < len(kv); i += 2 {
@@ -247,6 +325,15 @@ func (a *Agent) Cookies(kv ...string) *Agent {
 	return a
 }
 
+// CookiesBytesKV sets multiple 'key: value' cookies.
+func (a *Agent) CookiesBytesKV(kv ...[]byte) *Agent {
+	for i := 1; i < len(kv); i += 2 {
+		a.req.Header.SetCookieBytesKV(kv[i-1], kv[i])
+	}
+
+	return a
+}
+
 // Referer sets Referer header value.
 func (a *Agent) Referer(referer string) *Agent {
 	a.req.Header.SetReferer(referer)
@@ -254,6 +341,13 @@ func (a *Agent) Referer(referer string) *Agent {
 	return a
 }
 
+// RefererBytes sets Referer header value.
+func (a *Agent) RefererBytes(referer []byte) *Agent {
+	a.req.Header.SetRefererBytes(referer)
+
+	return a
+}
+
 // ContentType sets Content-Type header value.
 func (a *Agent) ContentType(contentType string) *Agent {
 	a.req.Header.SetContentType(contentType)
@@ -261,6 +355,13 @@ func (a *Agent) ContentType(contentType string) *Agent {
 	return a
 }
 
+// ContentTypeBytes sets Content-Type header value.
+func (a *Agent) ContentTypeBytes(contentType []byte) *Agent {
+	a.req.Header.SetContentTypeBytes(contentType)
+
+	return a
+}
+
 /************************** End Header Setting **************************/
 
 /************************** URI Setting **************************/
@@ -272,6 +373,13 @@ func (a *Agent) Host(host string) *Agent {
 	return a
 }
 
+// HostBytes sets host for the uri.
+func (a *Agent) HostBytes(host []byte) *Agent {
+	a.req.URI().SetHostBytes(host)
+
+	return a
+}
+
 // QueryString sets URI query string.
 func (a *Agent) QueryString(queryString string) *Agent {
 	a.req.URI().SetQueryString(queryString)
@@ -279,6 +387,13 @@ func (a *Agent) QueryString(queryString string) *Agent {
 	return a
 }
 
+// QueryStringBytes sets URI query string.
+func (a *Agent) QueryStringBytes(queryString []byte) *Agent {
+	a.req.URI().SetQueryStringBytes(queryString)
+
+	return a
+}
+
 // BasicAuth sets URI username and password.
 func (a *Agent) BasicAuth(username, password string) *Agent {
 	a.req.URI().SetUsername(username)
@@ -287,6 +402,14 @@ func (a *Agent) BasicAuth(username, password string) *Agent {
 	return a
 }
 
+// BasicAuthBytes sets URI username and password.
+func (a *Agent) BasicAuthBytes(username, password []byte) *Agent {
+	a.req.URI().SetUsernameBytes(username)
+	a.req.URI().SetPasswordBytes(password)
+
+	return a
+}
+
 /************************** End URI Setting **************************/
 
 /************************** Request Setting **************************/
@@ -298,6 +421,13 @@ func (a *Agent) BodyString(bodyString string) *Agent {
 	return a
 }
 
+// Body sets request body.
+func (a *Agent) Body(body []byte) *Agent {
+	a.req.SetBody(body)
+
+	return a
+}
+
 // BodyStream sets request body stream and, optionally body size.
 //
 // If bodySize is >= 0, then the bodyStream must provide exactly bodySize bytes
diff --git a/client_test.go b/client_test.go
index 6108a123..c28d2954 100644
--- a/client_test.go
+++ b/client_test.go
@@ -283,7 +283,7 @@ func Test_Client_UserAgent(t *testing.T) {
 	})
 }
 
-func Test_Client_Agent_Headers(t *testing.T) {
+func Test_Client_Agent_Set_Or_Add_Headers(t *testing.T) {
 	handler := func(c *Ctx) error {
 		c.Request().Header.VisitAll(func(key, value []byte) {
 			if k := string(key); k == "K1" || k == "K2" {
@@ -296,11 +296,17 @@ func Test_Client_Agent_Headers(t *testing.T) {
 
 	wrapAgent := func(a *Agent) {
 		a.Set("k1", "v1").
-			Add("k1", "v11").
-			Set("k2", "v2")
+			SetBytesK([]byte("k1"), "v1").
+			SetBytesV("k1", []byte("v1")).
+			AddBytesK([]byte("k1"), "v11").
+			AddBytesV("k1", []byte("v22")).
+			AddBytesKV([]byte("k1"), []byte("v33")).
+			SetBytesKV([]byte("k2"), []byte("v2")).
+			Add("k2", "v22")
+
 	}
 
-	testAgent(t, handler, wrapAgent, "K1v1K1v11K2v2")
+	testAgent(t, handler, wrapAgent, "K1v1K1v11K1v22K1v33K2v2K2v22")
 }
 
 func Test_Client_Agent_Connection_Close(t *testing.T) {
@@ -324,7 +330,8 @@ func Test_Client_Agent_UserAgent(t *testing.T) {
 	}
 
 	wrapAgent := func(a *Agent) {
-		a.UserAgent("ua")
+		a.UserAgent("ua").
+			UserAgentBytes([]byte("ua"))
 	}
 
 	testAgent(t, handler, wrapAgent, "ua")
@@ -338,8 +345,10 @@ func Test_Client_Agent_Cookie(t *testing.T) {
 
 	wrapAgent := func(a *Agent) {
 		a.Cookie("k1", "v1").
-			Cookie("k2", "v2").
-			Cookies("k3", "v3", "k4", "v4")
+			CookieBytesK([]byte("k2"), "v2").
+			CookieBytesKV([]byte("k2"), []byte("v2")).
+			Cookies("k3", "v3", "k4", "v4").
+			CookiesBytesKV([]byte("k3"), []byte("v3"), []byte("k4"), []byte("v4"))
 	}
 
 	testAgent(t, handler, wrapAgent, "v1v2v3v4")
@@ -351,7 +360,8 @@ func Test_Client_Agent_Referer(t *testing.T) {
 	}
 
 	wrapAgent := func(a *Agent) {
-		a.Referer("http://referer.com")
+		a.Referer("http://referer.com").
+			RefererBytes([]byte("http://referer.com"))
 	}
 
 	testAgent(t, handler, wrapAgent, "http://referer.com")
@@ -363,13 +373,14 @@ func Test_Client_Agent_ContentType(t *testing.T) {
 	}
 
 	wrapAgent := func(a *Agent) {
-		a.ContentType("custom-type")
+		a.ContentType("custom-type").
+			ContentTypeBytes([]byte("custom-type"))
 	}
 
 	testAgent(t, handler, wrapAgent, "custom-type")
 }
 
-func Test_Client_Agent_Specific_Host(t *testing.T) {
+func Test_Client_Agent_Host(t *testing.T) {
 	t.Parallel()
 
 	ln := fasthttputil.NewInmemoryListener()
@@ -383,7 +394,8 @@ func Test_Client_Agent_Specific_Host(t *testing.T) {
 	go app.Listener(ln) //nolint:errcheck
 
 	a := Get("http://1.1.1.1:8080").
-		Host("example.com")
+		Host("example.com").
+		HostBytes([]byte("example.com"))
 
 	utils.AssertEqual(t, "1.1.1.1:8080", a.HostClient.Addr)
 
@@ -402,7 +414,8 @@ func Test_Client_Agent_QueryString(t *testing.T) {
 	}
 
 	wrapAgent := func(a *Agent) {
-		a.QueryString("foo=bar&bar=baz")
+		a.QueryString("foo=bar&bar=baz").
+			QueryStringBytes([]byte("foo=bar&bar=baz"))
 	}
 
 	testAgent(t, handler, wrapAgent, "foo=bar&bar=baz")
@@ -420,7 +433,8 @@ func Test_Client_Agent_BasicAuth(t *testing.T) {
 	}
 
 	wrapAgent := func(a *Agent) {
-		a.BasicAuth("foo", "bar")
+		a.BasicAuth("foo", "bar").
+			BasicAuthBytes([]byte("foo"), []byte("bar"))
 	}
 
 	testAgent(t, handler, wrapAgent, "foo:bar")
@@ -438,6 +452,18 @@ func Test_Client_Agent_BodyString(t *testing.T) {
 	testAgent(t, handler, wrapAgent, "foo=bar&bar=baz")
 }
 
+func Test_Client_Agent_Body(t *testing.T) {
+	handler := func(c *Ctx) error {
+		return c.Send(c.Request().Body())
+	}
+
+	wrapAgent := func(a *Agent) {
+		a.Body([]byte("foo=bar&bar=baz"))
+	}
+
+	testAgent(t, handler, wrapAgent, "foo=bar&bar=baz")
+}
+
 func Test_Client_Agent_BodyStream(t *testing.T) {
 	handler := func(c *Ctx) error {
 		return c.Send(c.Request().Body())