This app was mentioned in 4 comments, with an average of 1.00 upvote
It's hard to find something that auto selects the object and background.
The best option I can recommend is using Portrait Lens. You select the object and background with some lines and it will do the work. It gives the option to change saturation/blur/brightness/etc.. for each one.
Another option is AfterFocus app, but IMO Portrait Lens is much better, simpler and "smarter" when it comes to the selection of object and background + it's completly free (AfterFocus has pro paid version). It's not updated since 2014 but believe me it's so awesome and working fine on my phone (worked on Android 5.1 and working on 6.0), you won't need more than some lines to have the work done. Good luck!
PS: that was my review, Play Store reviews don't look that good, give it a try anyway :P