Duplicate Detection behavior

Hello Everyone,

I have a client requirement where they don't want to make use of Out of the box Duplicate Process.

In Lead we have 2 fields Existing Account and Company Name - Is it possible to use 1 field and apply Duplicate check in one field.

For Example: If Company Name is "ITC Limited" then there should be pop up where system will show all relevant search for this lead. It will look into

Leads, Accounts and Contacts and if duplicate exists user can check record and if use selected Account Name from duplicate then Address details in lead should be updated.

I have implemented using Existing Account and have created a Real time time workflow to populate all related fields from Account.

I am struggling to check if it is possible to apply Global Search in text field "Company Name".

Please suggest.

Thank you:

Preeti