Searchable Drop down list

Greetings,

i would like to know how to create a searchable drop down list..

1. these are the different sheets that contains full details. for example the sheet "client"
sg1.png

2.these are the example of details in client tab... there are thousands of details. so im unable to do a normal drop down. thats why i would like to do a searchable drop down..
sg2.png

3.this is the master record... this is the tab ill be using to key in details.. now i need the drop down to work in this tab... for example if let say i wants to key in the details of a client in this master record.. this drop down list should show me the details which is gathered from the clients tab.
sg3.png

please help me...
thanking you in advance...

Check out this tutorial

http://www.youtube.com/watch?v=vkPoViUhkxU