Use Arel directly to substitute default "AND" operator with "OR" for joining where() chains

arel_hackery.rb

class Hackery < Arel::Visitors::ToSql
  def quack(o)
    "WHERE #{o.wheres.map { |x| visit x, nil }.join ' OR ' }"
  end
end

hack = Hackery.new(ActiveRecord::Base.connection)
condition1 = {:social_network_type => "facebook", :social_network_id => "555555"}
condition2 = {:social_network_type => "linkedin", :social_network_id => "555555"}
hack.quack(SocialUser.where(condition1).where(condition2))
# output =>
=begin
"WHERE ((`social_network_users`.`social_network_type` = 'facebook' AND `social_network_users`.`social_network_id` = '555555'))
 OR ((`social_network_users`.`social_network_type` = 'linkedin' AND `social_network_users`.`social_network_id` = '555555'))"
=end