membership type exists

Does the membership_type meta_key exist

$meta_query = array(
	'relation' => 'OR',
	array(
		'key'     => 'membership_type',
		'value'   => '1',
		'compare' => 'EXISTS',
	),
	array(
		'key'     => 'membership',
		'value'   => '1',
		'compare' => 'EXISTS',
	),
	array(
		'key'     => 'membership_id',
		'value'   => '1',
		'compare' => 'EXISTS',
	),
	array(
		'key'     => 'memb_type',
		'value'   => '1',
		'compare' => 'EXISTS',
	),
	array(
		'key'     => 'user_memb_type',
		'value'   => '1',
		'compare' => 'EXISTS',
	),
);