The main file for the display is \webapp\WEB-INF\classes\soy\autosearch\autosearch.soy, so you could overlay that and make changes. You'll also need to alter/override the corresponding CSS, altering things like .jive-spotlight-search-result to suit the wider layout you're after. It could be that you can make a lot of the alterations purely in CSS, since each section of the results is in a separate DIV.
Thank you very much for the reply!
Can I also do this using /template/global/include/spotlight-search.ftl OR \soy\autosearch\autosearch.soy and CSS is fine?
Please share your thoughts.