Meta query – Blue/Red items under 500 USD
Retrieve only blue OR red items, and under 500 USD.
$meta_query = array( 'relation' => 'AND', array( 'key' => 'price', 'value' => '500', 'compare' => '<', 'type' => 'NUMERIC', ), array( 'relation' => 'OR', array( 'key' => 'color', 'value' => 'blue', 'compare' => '=', ), array( 'key' => 'color', 'value' => 'red', 'compare' => '=', ), ), );