Setup Papertrail:

gem 'paper_trail'
rails g paper_trail:install --with-changes --with-associations

Add the following to the tracked model:

has_paper_trail

For example:

class Client < ActiveRecord::Base
  validates :name, :presence => true
  has_paper_trail
end

In rails_admin.rb:

...
config.audit_with :paper_trail, 'Admin', 'PaperTrail::Version'
...
history_index
history_show

There you are!