You will blow the fuse on your multimeter if you try to use the ohmmeter function. You can get a rough idea of internal resistance by connecting the meter probes, in DC volts mode, directly across the battery and recording the unloaded voltage - call this reading Voc. Now briefly connect a 100 ohm resistor (Rload) across the battery until your voltmeter reading settles, and record the new reading. Disconnect the resistor. Call this reading Vld.
Rint=Rload*(Voc-Vld)/Vld
If you only get a few millivolts change, your result will be inaccurate. You can use smaller resistance loads for more accuracy, but remember to use a resistor of appropriate wattage, or you will burn your resistor and/or your fingers. You will also discharge your battery more rapidly.
I'm not an expert on battery impedance measurements, but I think I would use an electronically pulsed load with a low duty cycle, measure the resulting voltage waveform across the battery using an oscilloscope, and calculate the resistance in a similar fashion.
Ron