- strpos: documentation ( source)
- str_replace: documentation ( source)
<?php
$data='{click} alskdjlk askljdlkasjd;wqoei alskdjaskld alskjdasl k lkasnzxcm,nzxma w';
if (strpos($data,'{click}')!== false) {
$data1=str_replace("{click}",'{clank}',$data);
}