You can use google webservice to map from address to coordinate:
or you use CLGeocoder functions on Mac to do the same.
Once you have all coordinates, you could load Google map in a web viewer and add dots for each point.
Creating a map for each client, especially on IOS devices and go, is easily done by mimicking the Contacts starter solution. There's a button that takes you to a google map with a pin.
For putting mulitple clients (found set) on an interactive map with pins, in a webviewer, I still find this to be the simplest:
Tim had some nice and usefull techniques that I use a lot
here is one for maps
and the other are here