The higher the resolution of the PDF; the better the chances of extracting Text from it.
If you have any version of Adobe Acrobat 9 and above; the task is pretty straight forward.
From the Menu – Document – OCR Text Recognition – Recognize Text using OCR (Single File) / Recognize Text in Multiple Files using OCR
Once this is done; you should be able to select; copy and search text from the document. You may also choose to save this file as a Word Document for easier editing. But you expect most of the formatting to be lost when saved to Word or any other editable format
If you do not have any licensed software and still want to get this done; there is a Online Solution available as well
They provide a Free Full Functional Demo worth 20 Credits (up to 62 pages)