WP_Meta_Query In 4.1

meta-query.php

$query = new WP_Query( array(
    'meta_query' => array(
        'relation' => 'OR',
        array(
            'relation' => 'AND',
            array(
                'key' => 'city',
                'value' => 'Miami',
            ),
            array(
                'key' => 'state',
                'value' => 'Ohio',
            ),
 
        ),
        array(
            'relation' => 'AND',
            array(
                'key' => 'city',
                'value' => 'Augusta',
            ),
            array(
                'key' => 'state',
                'value' => 'Maine',
            ),
 
        ),
    ),
) );