PHP Glob cannot open large files - "Allowed memory size of X bytes exhausted (tried to allocate Y bytes)"

Question

I'm assuming glob cannot open large files, as every time it tries to open 2 big files at once, it outputs: Fatal error: Allowed memory size of 536870912 bytes exhausted (tried to allocate 371490864 bytes) in C:\xampp\htdocs\mywebsite\results.php on line 15

Here is results.php:

<?php
error_reporting(E_ERROR | E_PARSE);
$file = glob('db/*', GLOB_BRACE);
$searchfor = $_GET['q'];
if (!$_GET['q']) {
     echo "Enter something.";
}
else {

// get the file contents, assuming the file to be readable (and exist)
$contents = implode(array_map(function ($v) {
    return file_get_contents($v);
}, glob(__DIR__ . "/db/*"))); // this is line 15

// escape special characters in the query
$pattern = preg_quote($searchfor, '/');

// finalise the regular expression, matching the whole line
$pattern = "/^.*$pattern.*\$/m";

// search, and store all matching occurences in $matches
    if (preg_match_all($pattern, $contents, $matches))
    {
    echo '<center>Results</center>';
    echo "<pre>";
    echo implode($matches[0]);
    echo "</pre><br></div>";
    }
    else
{
   echo "<center><br>No results found</center>";
}
}

whats suppose to happen is to output everything from those two files with the query that I add into the search engine, instead this memory error thing shows up.

Maybe there's something I'm missing or there's a way around it?

I've tried researching but nothing really popped up. Help?