Just be persistent. He is probably scared and hiding, which is why when you call for him he doesn't stray out to greet you.

I would look under bushes, in tight corners under stairwells, and anywhere a little one like that might possibly hide. Keep your ears open for his crying. We're actually a bit lucky we got some rain, so he shouldn't be too dehydrated at this point. He might, however, be getting hungry and try to wander near dumpsters and/or other areas where he might try to find discarded food.

I'm keeping my fingers crossed for you.