Put his litter box on your porch, along with an article of clothing with your scent on it. Cats have a wonderful sense of smell and will come to those items. Leave a window cracked nearby so that you can hear him. Post pictures around the neighborhood and on doors. Ask neighbors to keep an eye out and to check garages and sheds. Cats hide, usually fairly close by. They tend to come out after dark, so look for him then. Call and rattle a treat can if he likes those. If you put food out, stay close by, because it will also attract other animals that might scare him away. Don't leave it out very long. Also, go in person to shelters and vets' offices, and leave a picture and phone number there. I hope you find him!