A Cape Cod school employee has been arrested and charged with raping a 15-year-old student. The Plymouth district attorney’s office said that Robert Ward of Bourne was arraigned Thursday on three counts of rape of a child. Ward has since been fired from his job as an information technology specialist at Upper Cape Cod Regional Technical School in Bourne. A phone message left at an address listed for Ward was not immediately returned last night. Upper Cape Tech superintendent Kevin Farr said that on Wednesday, a student told a school staff member that the 15-year-old girl had an ‘‘inappropriate relationship’’ with Ward. Farr said he had Ward escorted off school property. He said staff members spoke with the 15-year-old’s mother that day, then called police.