qBittorrent official forums

Say I have a very big torrent with many big files, so I choose to download some of the files i need in order to not run out of disk space. When I'm done with the files I downloaded I want to delete the files to clear up some disk space.
Then download a few new files from the same torrent and continue in this cycle until I have downloaded everything I need.

What is the proper/best way of doing this in qBittorrent?