findstring.php

<?php

$string = 'http://meusite.com.br/wp-admin.php';
$BlackListURL = ["wp-admin.php", "admin", "administrator", "wp-login.php"];

/** Procure por uma parte da string no texto **/
function hasString($search, $text, &$found) {

	if (!is_array($search)) {
		$search = [
			$search,
		];
	}

	foreach ($search as $keys => $value) {
		$position = strpos($text, $value);

		if ($position !== false) {
			$found = $value;
			return true;
		}
	}

	return false;
}

#
$hasString = hasString($BlackListURL, $string, $found);

var_dump($hasString); // true
var_dump($found); // wp-admin.php