Rok,
Plastic SCM supports 'stashing'/'shelving' changes and it implements a mix of what Git and Perforce/TFS can do as you can find here: http://codicesoftware.blogspot.com/2012/02/shelving-stashing-introduced.html
Plastic SCM can:
- Apply the stashes through merging - like Git and unlike TFS
- Store the stash on server - like TFS and unlike Git
But, I think you're asking for a way to checkin only part of a file (hunks like in Git) which is something Plastic SCM can't do so far... An interesting feature but not yet there :P