locations

$meta_query = array(
	'relation' => 'OR',
	array(
		'key'     => 'locations',
		'value'   => '4|18|2',
		'compare' => 'REGEXP',
	),
	array(
		'key'     => 'other_locations',
		'value'   => '4|18|2',
		'compare' => 'REGEXP',
	),
);