$query = $this->db->select('*')->from('table');

$where = array();
$ft_min_word_len = mysql_result(mysql_query("SHOW VARIABLES LIKE 'ft_min_word_len'"), 0, 1);
preg_match_all("~[\\pL\\pN_]+('[\\pL\\pN_]+)*~u", stripslashes($_GET["search"]), $matches);

foreach ($matches[0] as $part) {
    if (iconv_strlen($part, "utf-8") < $ft_min_word_len) {
        $regexp = "[[:<:]]" . mysql_real_escape_string($part) . "[[:>:]]";
    $query->where("([z.cz_nazev] %sql OR [z.cz_popis] %sql)", $regexp, $regexp);
    }
}


$query->fetchAll();