Query meta

Get posts by meta:

$args = array(

	'meta_key' => 'my_key',

	'meta_value' => 'my_value',

	'meta_compare' => '!=' 

	// '=', '!=', '>', '>=', '<', '<=', 'LIKE', 'NOT LIKE', 'IN', 'NOT IN', 'BETWEEN', 'NOT BETWEEN'

);

query_posts( $args );

Get posts with ordering by meta:

$args = array(

	'orderby' => 'meta_value',

	'order' => 'DESC' // ASC

);

query_posts( $args );

Get posts by multiple meta:

query_posts( array(

	'post_type' => 'catalog',

	'meta_query' => array(

		array(

			'key' => 'price',

			'value' => array( 10, 20 ),

			'compare' => 'BETWEEN',

			'type' => 'numeric',

		),

		array(

			'key' => 'type',

			'value' => 'square',

			'compare' => 'NOT LIKE'

		)

	)

) );