Авторизация по e-mail [требует правки]

Помогите пожалуйста переделать данный код чтобы принимал email и логин.

if(isset($_POST['login']))
{
$query = "SELECT $MySQLi_userid_field,$MySQLi_username_field,$MySQLi_password_field,$MySQLi_status_field FROM `".$config['db']['pre'].$MySQLi_user_table_name."` WHERE $MySQLi_username_field='" . $_POST['username'] . "' AND $MySQLi_password_field='" . md5($_POST['password']) . "' LIMIT 1";
$query_result = mysqli_query($con,$query);
$row_count = mysqli_num_rows($query_result);
if($row_count>0){
    $info = mysqli_fetch_array($query_result);
    $user_id = $info[$MySQLi_userid_field];
    $username = $info[$MySQLi_username_field];
    $status = $info[$MySQLi_status_field];
    if($status != 2)
    {
        $_SESSION['id'] = $user_id;
        $_SESSION['username'] = $username;
        echo '<script type="text/javascript"> window.location = "index.php" </script>';
        exit;
    }
    else
    {
        if($info['status'] == 2)
            $error = $lang['ACCOUNTBAN'];
        else
            $error = $lang['USERNOTFOUND'];
    }
}
else
{
   $error = $lang['USERNOTFOUND'];
}
}

Название столбца - email