Search for multiple tags?

Well, I got it working by making my own own parse php as follows:

parse.php

<?php

$tags = $_POST['tag'];
$search = $_POST['s'];
$count = count($tags);

$i = 0;
if(!empty($search))
    $uri = "https://example.com/?s=$search&";
else
    $uri = "https://example.com/?tag=";
foreach($tags as $name=>$value) {
    ++$i;
    if($i !== $count)
        $uri .= $value."+";
    else
        $uri .= $value;
}

header("Location: $uri");
exit;
?>

And of course, changing the original form action to point to parse.php and the method to POST.

Probably not the best way of doing this, but for now it works. If someone can give me a better or cleaner answer, please do.