Search and replace strings over multiple lines using CMD or PowerShell (Windows)

I am running a batch script to modify theme files.
I need a command that will find a block of PHP code in the directory given and replace it with a string that has carriage returns

i.e
<?php [php string with & || == symbols] ?>
<div class="class">
<ul>
</ul>
</div>
<?php ?>

I am currently using the FART utility to find and replace single strings (http://fart-it.sourceforge.net/)
eg: fart -r -C -c "DIRECTORY\FILE" "string search" "string replace"

I would ideally like to find a way to still use this utility.
I need a windows solution using either CMD or Powershell which I can invoke via CMD

Its an urgent issue so I would need someone who is online that can work through this issue with me to resolve asap