$my_query = new WP_Query( array( 'post_type' => 'post', 'meta_query' => array( array( 'key' => 'project_cat', 'value' => 'my-value', ) ), // Other query properties ) );
$my_query = new WP_Query( array( 'post_type' => 'post', 'meta_query' => array( array( 'key' => 'project_cat', 'value' => 'my-value', ) ), // Other query properties ) );