pagination and model calculated fields

class Client has_many :placements class Placement belongs_to :clients

class Client...   def current_client     if Placement.find(:first,     :conditions => ["discharge_date IS NULL AND accepted IS true \     AND client_id = ?", self])       return true     else       return false     end   end

using paginator my clients_controller.rb

  @pager =     :conditions => cond.to_sql), 12) do |offset, per_page|     Client.find(:all, :limit => per_page,     :conditions => cond.to_sql,     :include => :case_manager,     :order => sortby,     :offset => offset)   end

is there any way that I can 'sort' by current_client (not a table field) and paginate properly?