How to Ordering by user meta

Replies: 0

I am learning WordPress meta query. I am trying to fetch users with asc order of last_name & first_name. My code is like below.

if($_POST['orga_id']) {
		$users_query = array(
			'meta_query' => array(
				'relation' => 'AND',
				array(
					'relation' => 'OR',
					array(
						'key'     => 'first_name',
						'value'   => $_POST['search'],
						'compare' => 'LIKE'
					),
					array(
						'key' 		=> 'last_name',
						'value' 	=> $_POST['search'],
						'compare' 	=> 'LIKE',
					),
				),
				array(
					'key' 		=> 'organisation',
					'value' 	=> $_POST['orga_id'],
					'compare' 	=> 'LIKE',
				),
				array(
					'key' 		=> 'available',
					'value' 	=>  1,
					'compare' 	=> '=',
				),			
			)
		);
	} else {
		$users_query = array(
			'meta_query' => array(
				'relation' => 'AND',
				array(
					'relation' => 'OR',
					array(
						'key'     => 'first_name',
						'value'   => $_POST['search'],
						'compare' => 'LIKE'
					),
					array(
						'key' 		=> 'last_name',
						'value' 	=> $_POST['search'],
						'compare' 	=> 'LIKE',
					),
				),
				array(
					'key' 		=> 'available',
					'value' 	=>  1,
					'compare' 	=> '=',
				),			
			)
		);
	}

How can I fetch users with asc order of last_name & first_name ?