I don't know if it's only my problem or is there someone else who has it.
Namely, when I play against QPR in their stadium (Loftus Road) thin horizontal black line appears on the middle of the screen.
Is this a common bug in the game or some mistake in my database? My Fifa installation is clean, no any db patch (except gameplay patch). Repair game option doesn't help. Anyone know what's the problem?
So now I'm confused. You said your game was clean, and that you only have a game play patch installed. If so, that's not the issue. Only a graphics patch would cause that.
That said, looking at the screen, the black line runs at an angle parallel to the touchline, indicating that it is not a graphics card issue, but an issue with your turf files. If it were a graphics card issue, the line would run horizontally straight across the monitor screen. So it does look like you installed some kind of turf/graphics patch.
Simple solution: Rename your current files FIFA 16 X. Paste your original unmodded back-up files into your Origin folder. Run the game, if the line is gone you know the patch is the issue.