Is it possible to make with pure PHP split screen where I will show results from 3 major search engines seperately. It's just for learning, not for commercial use. I tried with frameset, but not sure how to do the rest, cause I have to include 3 different .html documents in frames
I would do this with jQuery for loading the front end and then set your PHP script to collect the results for each search engine using the Ajax commands.
PHP has no impact on the client-side layout, it is primarily a server-side language. Use HTML iFrames or like HuggyEssex said use a client-side language like Javascript.