Billing Meta

$meta_query = array(
	'relation' => 'OR',
	array(
		'key'     => '_billing_first_name',
		'compare' => '=',
	),
	array(
		'key'     => '_billing_last_name',
		'compare' => '=',
	),
	array(
		'key'     => '_billing_phone',
		'compare' => '=',
	),
);