<?php
	global $wpdb;

	$user_sites = array('12', '13', '14');
	$conditions_sites = array();

	foreach ($user_sites as $id_site) {
		$conditions_sites[] = "($wpdb->postmeta.meta_key = 'sites_lies' AND CAST($wpdb->postmeta.meta_value AS CHAR) LIKE '".serialize($id_site)."')";
	}

	$query = "SELECT
	$wpdb->posts.ID
	FROM $wpdb->posts
	INNER JOIN $wpdb->postmeta ON ($wpdb->posts.ID = $wpdb->postmeta.post_id)
	WHERE 1=1
	AND $wpdb->posts.post_type = 'post'
	AND ($wpdb->posts.post_status = 'publish' OR $wpdb->posts.post_status = 'private')
	AND (
		".implode(' OR ',$conditions_sites)."
	)
	GROUP BY $wpdb->posts.ID
	ORDER BY $wpdb->posts.post_date DESC";

	$results = $wpdb->get_results($query);
?>