$mytbl = new MyTable();
$myresults = $mytbl->fetchAll(
        "(col1 LIKE 'val1' AND col2 LIKE 'val2')
        OR (col1 LIKE 'val2' AND col2 LIKE 'val1'))
        AND col3 = 'val3');

$mytbl->fetchAll(
        "(col1 LIKE ? AND col2 LIKE ?)
        OR (col1 LIKE ? AND col2 LIKE ?))
        AND col3 = ?,
        array(
            $db->quote($val1),
            $db->quote($val2),
            $db->quote($val2),
            $db->quote($val1),
            $db->quote($val3)));

$mytbl->fetchAll(
        $mytbl->select()
            ->where("(col1 LIKE ? AND col2 LIKE ?)
                    OR (col1 LIKE ? AND col2 LIKE ?)) AND col3 = ?,
                    array(
                        $db->quote($val1),
                        $db->quote($val2),
                        $db->quote($val2),
                        $db->quote($val1),
                        $db->quote($val3))));

$mytbl->fetchAll(
        "(col1 LIKE ? AND col2 LIKE ?)
        OR (col1 LIKE ? AND col2 LIKE ?))
        AND col3 = ?",
        array($val1, $val2, $val3, $val4, $val5));