Single base - Editable by different team members to whom the records are assigned

[Mangadeep_Yerra]

My organization has 10 employees. We all work on a single base. But few of the records in each base will be handled by different employees.

I want to restrict employees to view and edit only those records for which they are the collaborators.
But as an employer I want to view and edit all the information in the records.

I also want to restrict my employees from accessing few columns.

Can you please let me know how to proceed. Thanks in advance