class Transaction < ActiveRecord::Base
  ...

  searchable do
    text :description
    integer :id
    float :amount
  end

  ...
end

def search
  @search = Transaction.search do
    any_of do
      with(:amount, params[:search])
      with(:id, params[:search])
      fulltext(params[:search])
    end
  end

  @transactions = @search.results
end