The Use case for this Scenario would be, Avoiding duplication of Leads so how does it works? This would be helpful while Creating a Lead Search/check whether Related Account exists or not in Salesforce, if found go ahead edit else click Create Lead Tab to Create a new Lead record.

How Visualforce page looks like?

Demo Video

Please check source code at following links

Visualforce Page, http://bit.ly/leadsearch-vfpage

Apex Class, http://bit.ly/leadSearch-apexClass

Please feel free to comment below If you're facing any issues

Thank you