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
      return false

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)

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