OR's together provided scopes, returning an ActiveRecord::Relation. This implementation is smart enough to not only handle your _where_ clauses, but it also takes care of your joins! *Note* This is a work in progress, so it has room to grow

or_scope.rb

module ActiveRecord::OrScope
  def self.included(base)
    base.send :extend, ClassMethods
  end
  
  module ClassMethods
    def or_scope(*scopes)
      conditions = 
        scopes
          .map { |scope| "(#{scope.where_clauses.map{ |clause| "(#{clause})"}.join(" AND ")})" }
          .join(" OR ")
          
      relationships =
        scopes
          .map { |scope| scope.joins_values }
          .flatten
          .uniq
          
      joins(*relationships).where(conditions)
    end
  end
end