Get custom field outside wordpress loop on new php page

Question

I want to get a specific custom field value to display outside the wordpress loop in a new php page. right now im using the code below, which is doing what i want but in a ugly way. i need to exclude all custom fields except the one i want to get. instead of excluding, i would be happy if someone could provide me with a better code. so i can get just the custom field value that i want

    require_once($_SERVER['DOCUMENT_ROOT'] . '/wp-load.php');
    $postid = $_GET["postid"];;

    $custom = get_post_custom($postid);

    foreach ($custom as $key => $value) {
    if (($key != '_edit_lock' && $key != 'cwp_bar_icon' && $key !=     '_edit_last' && $key != 'send_onesignal_notification'&& $key != 'wp_noextrenallinks_mask_links'&& $key != 'wpb_post_views_count'&& $key != 'mp3'&& $key != 'wpb_post_views_count'&& $key != '_encloseme'&& $key != 'wpb_post_views_count'&& $key != '_pingme'&& $key != 'wpb_post_views_count'&& $key != '_is_video'&& $key != '_thumbnail_id'

))
        echo '<meta http-equiv="refresh" content="0; URL=' . $value[0] . '">';
}

Answer 1

ok got it myself didnt thought it would be that simple

require_once($_SERVER['DOCUMENT_ROOT'] . '/wp-load.php');
$postid = $_GET["postid"];

$custom = get_post_custom($postid);

 {

        echo '<meta http-equiv="refresh" content="0; URL= ' . get_post_meta($postid, 'custom-filed-key', true) . ' ">';
}