Making body background clickable with minimal changes

I'd like to make the background image on my website clickable with minimal changes to the html code (as there's lots of pages that would need changing). If it is possible to restrict it to CSS/JQuery that would be really handy. The website is: [login to view URL] and it is the Gigabyte background image that I want to make click-able without affecting any other part of the website. The coder will provide me with the code to upload to the site, no direct access or copies of the files will be given.