Make a click on client side

<textbox id="campoMensagem" multiline="true" width="100%" height="35px" type="text" xmlns:w="client">
			<attribute w:name="onKeyDown"><![CDATA[
				if(event.keyCode == 13 ){
					var btn = jq("$btnEnviar");
					zk.Widget.$(btn).onClick;
				}
			]]></attribute>
</textbox>