Passing arguments to ransackers

Question

I'm using Rails 3.2 and Ransack gem. Everything works fine but I would like to create some custom ransackers with passable arguments. For example:

ransacker args: [arg1] do |parent|
  Arel::Nodes::SqlLiteral.new("table.field_1 = #{arg1} AND table.field_2")
end

Something like this would greatly enchance ransackers usability but I didn't find any info about it. Is there a way to do something like this?