users get with cumple

// WP_User_Query arguments
$args = array(
	'meta_query'     => array(
		'relation' => 'AND',
		array(
			'key'     => 'fecha_cumpleanos',
			'compare' => 'NOT EXISTS',
		),
	),
	'count_total'    => true,
	'fields'         => array( 'user_email', 'id', 'user_nicename', 'first_name', 'last_name' ),
);

// The User Query
$user_query = new WP_User_Query( $args );

// The User Loop
if ( ! empty( $user_query->results ) ) {
	foreach ( $user_query->results as $user ) {
		// do something
	}
} else {
	// no users found
}