I'm not sure I'm "with you" on that one. Using an ohm meter on what? Do you plan on having, for example, a 1k, 5k, 10, and so forth 1% tolerance calibration resistor? Because, when you run your sketch, it needs to know the value that is exactly at the center of the +/-15% test range. Most meters are only accurate to about 0.1%-0.5% accuracy anyway...
I agree, you need to refine and present a more "high level" system design, before you even touch the coding keyboard...
It isn't that the circuit you posted won't work, it's that you need to define better, how it will be used.