friendica/view/templates/contacts-head.tpl

<script>
$(document).ready(function() {
	$("#contacts-search").contact_autocomplete(baseurl + '/acl', 'a', true);
 

	$("#contacts-search").keyup(function(event){
		if(event.keyCode == 13){
			$("#contacts-search").click();
		}
	});
	$(".autocomplete-w1 .selected").keyup(function(event){
		if(event.keyCode == 13){
			$("#contacts-search").click();
		}
	});
});
</script>